Home >> Community Medicine >> ForumTopic: Todays main question on statistics
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| superbdoc Total Posts: 273 | Posted: Tue Oct 14, 2008 07:36 pm Question: If the birth weight of each of the 10 babies born in a hospital in a day is found to be 2.8 kg., then the standard deviation of this sample will be ? A) 2.8 B) 0 C) 1 D) 0.28 I am not good at maths...But how come the ans is given as B...  |
| jemzcal Total Posts: 127 | Posted: Tue Oct 14, 2008 09:19 pm hey standard deviation measures the deviation of the observed values from the mean. so since the observed values are not different from the mean, there is no question of any deviation. if you want to complicate things, you can always substitute the values in the formula for s.d and come up with the same answer |
| superbdoc Total Posts: 273 | Posted: Wed Oct 15, 2008 01:15 am Oh No...Again a logical twister.....this is getting interesting...thanx mate...  |
| superbdoc Total Posts: 273 | Posted: Wed Oct 15, 2008 06:35 pm The number of malaria cases reported during the last 10 years in a town are given below: 250,320,190,300,5000,100,260,350,320& 160. The epidemiologist wants to find out the average number of malaria cases reported in that town during the last 10 years. The most appropriate measure of average for this data will be ? A) Arithmetic mean B) Mode C) Median D) Geometric mean DOes any1 help..? |
| jemzcal Total Posts: 127 | Posted: Wed Oct 15, 2008 08:17 pm now the confusion has to be between mean and median because you can straightaway rule out the other two. mode because there are no repeating values and g mean because there is no geometric progression here now the highest observation in the data is 5000 and the lowest is 160. and there are no values near 5000. if we take mean the value would be falsely shifted to right to accomodate the 5000. so logically median is the better option |
| superbdoc Total Posts: 273 | Posted: Wed Oct 15, 2008 09:41 pm So as far as I get it,wide variations and lack of repeated values seal the issue in fav of Median... Jemzcal,dude u r too gud...thnX..  |
| superbdoc Total Posts: 273 | Posted: Thu Oct 16, 2008 09:08 pm In a group of patients presenting to a hospital emergency with abdominal pain, 30% of patients have acute appendicitis, 70% of patients with appendicitis have a temperature greater than 37.5°C and 40% of patients without appendicitis have a temperature greater than 37.5°C. Considering these findings, which of the following statements is correct ? A) The sensitivity of temperature greater than 37.5°C as a marker for appendicitis is 21/49 B) The specificity of temperature greater than 37.5°C as a marker for appendicitis is 42/70 C) The positive predictive value of temperature greater than 37.5°C as marker for appendicitis is 21/30 D) The specificity of the test will depend upon the prevalence of appendicitis in the population to which it is applied Is it a repeat qn.. |
| jemzcal Total Posts: 127 | Posted: Thu Oct 16, 2008 09:17 pm you bet. you can sort this one out by drawing a 2*2 table which would come as appendicits + - temp>37.5 + 21 28 - 09 42 total 30 70 |
| jemzcal Total Posts: 127 | Posted: Thu Oct 16, 2008 09:18 pm sorry bout the allignment |
| superbdoc Total Posts: 273 | Posted: Thu Oct 16, 2008 09:22 pm your helping mentality is appreciable...not only u the entire team here is helpful.... |